The height off the ground, in feet, of a squirrel leaping from a tree branch is given by the function H(x) = –16x*2 + 24x + 15, where x is the number of seconds after the squirrel leaps. How many seconds after leaping does the squirrel reach its maximum height?

A.
1.33 s

B.
0.50 s

C.
0.75 s

D.
1.00 s